The present invention relates to protective clothing and, more particularly, to a thermal liner which may be used in apparel such as fire fighter's turnout apparel, to provide thermal insulation for the wearer of such apparel.
It will be appreciated that it is important to provide effective thermal insulation for a fire fighter in order to enable him to approach a fire closely and also to protect him in instances of unexpected exposure to high temperatures. A type of protective apparel, termed turnout clothing, has been developed which provides adequate protection for a fire fighter under the most commonly experienced structural fire conditions. The clothing typically includes a three-quarter length turnout coat and a pair of waist high pants that are held in place by suspenders. Alternatively, some fire fighters use a short, waist-length coat and bib style pants in combination or a one piece type garment. Regardless of the garment or garments selected, the goal is to provide continuous environmental protection over the fire fighter's body.
For turnout apparel a multi-layer construction has been utilized in the past. The outermost layer of fabric, termed the outer shell, is made of a flame resistant material, such as Nomex fabric, which also provides resistance to slashing, tearing, and abrasion. Underlying the outer shell fabric is a layer which is water impermeable, termed a vapor barrier, which is attached by snaps or by other appropriate means to the outer shell. The vapor barrier prevents moisture from the fire fighting environment from wetting the innermost layer, termed the thermal liner. The thermal liner may also be attached to the vapor barrier by snaps or by some other arrangement to the vapor barrier. Typically the thermal liner is made of Nomex quilt, wool, nylon and polyester quilt, or cotton flannel. The purpose of the thermal liner is to provide thermal insulation to protect the fire fighter. Additionally, thermal insulation is also provided by the air layer between the outer shell and the vapor barrier and by the air layer between the vapor barrier and the thermal liner. In some constructions, the vapor barrier has been constructed as a part of the thermal liner, such as by directly coating a flannel thermal liner with neoprene to form a vapor barrier skin. Although the air layer between the thermal liner and the separate vapor barrier is lost in such a combination construction, nevertheless, such construction has been found to provide adequate insulation.
As may be appreciated, the thermal insulative properties of the thermal liner material are dependent, in large part, upon keeping both the material and the air held by the material dry. It has been determined that where a high level of physical exertion is required of a fire fighter, sweat rates of up to 2000 grams per hour can occur and, with prolonged used of the fire fighter garment, can cause wetting of the thermal liner and the entrapped air, greatly reducing its insulation properties.
Accordingly, it is seen that there is a need for improved fire fighter protective apparel in which the thermal insulative properties of the apparel do not deteriorate during use.